chore: sync uv.lock own-version to the released 2.8.0 (#128)

## Summary

Release 2.8.0 (#125) bumped `pyproject.toml` to 2.8.0 but the committed
`uv.lock` still recorded `agentscore-commerce` at 2.7.2. `uv.lock`
embeds the project's own version, so a version bump leaves the lock
stale unless `uv lock` is re-run in the same change. This syncs the
lock's own-version line to 2.8.0.

`uv lock` resolves 141 packages with no dependency change; the only diff
is the own-version line. The published 2.8.0 wheel is unaffected (the
lock's own-version line is metadata, not shipped), so no re-release is
needed.

Worked with: Varun.

## Type of change

- [x] Docs, tests, or internal maintenance only

## Public API

None.

## Test plan

`uv lock` re-run produced a single-line diff (2.7.2 to 2.8.0) and no
dependency changes. No code changed. CI (ruff, format, ty, pytest) is
the gate.

## Checklist

- [ ] Tests cover the new behavior, and the suite passes locally
- [x] Lint, format, and type checks pass
- [x] Docs and README examples updated if the public surface changed
- [x] No secrets, credentials, or personal data in the diff or the tests

Author: vvillait88